I bought a Superchips Cortex about a week ago. I downloaded the software and updated it as soon as I got it, and installed it onto my truck. I had read on the website where they estimated a 12HP and 15Torque increase on the 4.8L V-8, and had read countless testimonials on several websites stating that the cortex was amazing. I used the built it 1/4 mile timer on the cortex to record my data. Stock tune on 91 octane gas: 17.33@85. I thought it was slow, not THAT slow, but it is what it is. I installed the "performance" mode and increased my shift firmness and ran a blistering 17.33@87. My 60' decreased by .2 using the same launching techniques, and beleive me, there was no wheelspin. There were some things I liked about this programmer: The 1/4 mile feature was cool, and it gave you all the incremental times and MPH. It can monitor a lot of engine data: TPS, Air Inlet Temp, Engine Load, and many more. I bought it to correct my speedo once I get my 4.10's installed and for a little power gain. I am sending it back, and am considering the Bullydog Power Pup or the SCT. Don't get me wrong, I'm not expecting Diesel type power gains, but I don't think a tenth or two is too much to expect for $350.